The standard calculator application of all psion PDA is convenient for common usage, but it is not powerfull enough for engineers, students and scientific who often need advanced functions in order to manipulate matrices, compound numbers and so on. Since these were my own needs too, I have build a new calculator for Psion PDA. My model was the HP48 because it is surely the best calculator for these needs, even if beginners are generally lost with RPN

Psion48 has the same commands as the HP48, and a similar graphical interface. It uses the RPN (Reversed polish Notation) with a stack that can be filled with any mathematical data type: reals, integers in any base, compound numbers, matrices, etc.

you can see screen copies of the software in the next pages, and even download it to test it.